1. Technical Field
The present invention relates to a reclining apparatus suitable for adjusting an angle of incline of a seat back, for example, in a seat for an automobile.
2. Background Art
In general, in the case of sitting on a seat of an automobile and adjusting an angle of a seat back, a sitting person operates a canceling lever of a reclining apparatus so as to cancel an engaging condition of the seat back, thereby tilting backward the seat back by an upper half of the body of the sitting person, and forward tilting due to an elastic force of a spring provided in the reclining apparatus, so that the canceling lever is released at a desired position of the seat back so as to be engaged. FIG. 6 shows an embodiment of a conventional reclining apparatus. In FIG. 6, reference numeral 1 denotes a fixed plate and reference numeral 2 denotes a rotary plate. A semi-punched recessed portion 3 formed in accordance with a fine blanking is formed on one surface of the fixed plate 1. A slide gear 4 is received in the recessed portion 3 so as to freely slide in a vertical direction. The slide gear 4 is moved by a cam member 5 rotatably supported to the fixed plate 1, and a gear teeth portion 4a formed in a lower edge portion is detachably engaged with an internal gear 2a formed in the movable plate 2. FIG. 7 shows a structure in which a semi-punching process in a reverse direction to that in FIG. 6 is applied to a fixed plate 6, the slide gear 4 is slidably supported between convex portions 7 having guide surfaces 7a parallel to each other.
In this case, when the automobile is collided with the following car from the behind, a great load due to the passenger is applied to the seat back. Further, in the case that a shoulder anchor of the seat belt is attached to the seat frame, a great load of the passenger is applied to the seat back via a seat belt due to a head-on collision of the automobile. Further, in such a case, a great moment is applied to the reclining apparatus, and in the conventional reclining apparatus mentioned above, the following problems are generated.
That is, in the reclining apparatus shown in FIG. 6, when a load FA is input to the internal gear 2a of the movable plate 2, there is generated a load balance of a lever in which a point A is a power point, a point B is a supporting point and a point C is a working point in FIG. 8, a load RB greater than the load FA is applied to the point B on the fixed plate 1 and the load RB is received in a narrow range B-Bxe2x80x2 of the convex portion 7. Accordingly, a load concentrated in the point B is increased and a portion near the point B deforms, so that as shown in FIG. 9, the slide gear 4 is inclined and an engagement of gear in a left side in the drawing is out of place, whereby it is impossible to maintain a proper engagement. Further, the reclining apparatus shown in FIG. 7 has the same problem mentioned above, and a condition of deformation is shown in FIGS. 10 and 11.
Accordingly, an object of the present invention is to provide a reclining apparatus which in the case that an excessive load is input to an internal gear, can receive the load in a sufficient span so as to prevent respective portions from deforming.
In accordance with the present invention, there is provided a reclining apparatus comprising: a fixed plate in which a guide portion having a pair of mutually opposing guide walls is provided; a shaft provided in the fixed plate so as to freely rotate around an axis in a horizontal direction; rotary plate relatively rotating around the shaft with respect to the fixed plate and in which an internal gear is provided along a circular arc around the shaft; a slide gear received between respective guide walls of the guide portion and freely moving between a lock position engaged with the internal gear and a lock canceling position moving apart from the internal gear; and a cam member mounted to the shaft and rotated by the shaft, thereby moving the slide gear to the lock position and the lock canceling position, wherein a wall portion protruding toward the internal gear and the guide portion in a plan view is provided in the slide gear, and a side surface of the wall portion is slidably in contact with the guide portion.
In accordance with the reclining apparatus of the present invention, the rotary plate can rotate with respect to the fixed plate by rotating the shaft so as to move the slide gear apart from the internal gear. In this condition, by rotating the seat back and engaging the slide gear with the internal gear at a desired position, the seat back is fixed. Further, in accordance with the present invention, since the wall portion protruding toward the internal gear and the guide portion in a plan view is provided in the slide gear, and the side surface of the wall portion is slidably in contact with the guide portion, the longer side surface than the side surface of the slide gear is the slidably contact surface with respect to the guide portion. Accordingly, the side surface which is long and has a large area is slidably in contact with the guide portion by setting a thickness of the wall portion to be equal to or more than a thickness of the slide gear, whereby a concentration of a load applied to the guide portion is reduced and a deformation thereof is restricted.
In this case, it is preferable to employ a structure in which the wall portion is protruded toward the cam member so as to project overall the slide gear from the wall portion in the thickness direction thereof. That is, this structure corresponds to a structure in which the slide gear protrudes in an inner side of one surface of the wall portion in a stepped shape. In accordance with the structure mentioned above, it is possible to form the slide gear by a semi-punching in accordance with a fine blanking, and it is possible to reduce a manufacturing cost.
Further, it is desirable to structure such that the cam member presses an immediately rear side of the gear teeth portion of the slide gear. Accordingly, the pressing force of the cam member linearly applies to the gear teeth portion of the slide gear and it is possible to prevent a backlash such as a float-up in a thickness direction of the slide gear from being generated. Further, there is an advantage that it is possible to make the thickness of the cam member the same as the thickness of the slide gear so as to make it thin. Further, among the conventional reclining apparatus, there is a structure in which a groove 15 with which a convex portion 14 of a cam member 11 is engaged at a time of moving a slide gear 10 to a lock canceling position is formed between a pressing member 12 pressed by the cam member 11 among the slide gear 10 and a gear teeth portion 13, as shown in FIG. 12. In accordance with this structure, there is a fear that a stress concentration is generated at a corner of a groove 15 or the like due to the pressing fore of the cam member 11 and a durability is reduced. However, in accordance with the present invention, such a fear can be removed by making the structure such that the cam member presses the immediately upper side of the gear teeth portion.